Mental stress objective screening for workers using urinary neurotransmitters.

BACKGROUND: Almost 10% of the population develop depression or anxiety disorder during their lifetime. Considering that people who are exposed to high stress are more likely to develop mental disorders, it is important to detect and remove mental stress before depression or anxiety disorder develops. We aimed to develop an objective screening test that quantifies mental stress in workers so that they can recognize and remove it before the disorder develops. METHODS: We obtained urine specimens from 100 healthy volunteers (49 men and 51 women; age = 48.2 ± 10.8 years) after they received medical checks and answered the Brief Job Stress Questionnaire (BJSQ). Participants were divided into high- and low- stress groups according to their total BJSQ scores. We further analyzed six urinary neurotransmitters (dopamine, serotonin, 5-hydoroxyindoleacetic acid, gamma-aminobutyric acid, homovanillic acid, and vanillylmandelic acid) using liquid chromatography-mass spectrometry to compare their levels between the two groups. RESULTS: We obtained the concentrations of the six analytes from 100 examinees and revealed that the levels of urinary dopamine (p = 0.0042) and homovanillic acid (p = 0.020) were significantly lower in the high-stress group than those in the low-stress group. No biases were observed between the two groups in 36 laboratory items. The stress index generated from the six neurotransmitter concentrations recognized high-stress group significantly. Moreover, we discovered that the level of each urinary neurotransmitter changed depending on various stress factors, such as dissatisfaction, physical fatigue, stomach and intestine problems, poor appetite, poor working environments, sleep disturbance, isolation, worry, or insecurity. CONCLUSION: We revealed that urinary neurotransmitters could be a promising indicator to determine underlying mental stress. This study provides clues for scientists to develop a screening test not only for workers but also for patients with depression.

Derivatization-assisted immunoassays: application for group-specific detection of potent methamphetamine and amphetamine enantiomers.

Reliable and feasible tools for detecting (S)-methamphetamine [(S)-MAP] and (S)-amphetamine [(S)-AP] are required for regulating their illicit circulation. Antibodies that react equally to these stimulants are desirable for this purpose, but have been difficult to generate because of the crucial difference between their characteristic structures: i.e., N-methylamino (MAP) and amino (AP) groups. Furthermore, their small molecular masses (Mr < 150) have hampered the generation of high-affinity antibodies. To overcome these problems, we converted (S)-MAP and -AP into their 2-(trimethylsilyl)ethyl carbamate forms, Teoc-(S)-MAP and -AP, respectively, as surrogate analytes. The Teoc-derivatization not only increases their molecular masses, but also masks their structural differences. We generated a novel monoclonal antibody that showed a satisfactory affinity to Teoc-(S)-MAP residues (Kd = 13 nM as the IgG form) and developed a competitive enzyme-linked immunosorbent assay (ELISA) using microplates containing immobilized Teoc-(S)-MAP residues. Almost overlapping dose-response curves were obtained for Teoc-(S)-MAP and -AP, with the limit of detection of 0.078 and 0.10 ng per assay, respectively. A fixed amount of test powder sample (1 mg) was derivatized with Teoc-O-succinimidyl for 5 min, and subjected to ELISA using Teoc-(S)-MAP as the calibration standard. Under this protocol, (S)-MAP and -AP were converted to their Teoc derivatives with 30% and 34% yield, respectively, determined using ELISA as "Teoc-(S)-MAP equivalent," being distinguished from the derivatization products of (R)-MAP, (R)-AP, ephedrine, (S)-methylenedioxymethamphetamine, tyramine, dopamine, and ß-alanine. This ELISA detected as little as 10 µg of (S)-MAP and -AP, and (S)-MAP in urine obtained from (S)-MAP-administered rats. Immunochromatography devices were also developed using gold nanoparticles coated with the monoclonal antibody, with which 0.10 mg of (S)-MAP and -AP was detected by the naked eye. We conclude that the present derivatization-assisted immunoassays may be useful for the detection of (S)-MAP and/or -AP in early stage screening of suspicious substances.